Bucket position indicator



1962 J. o. RUNCI :ETAI. 3,017,046

BUCKET POSITION INDICATOR Filed May 11, 1959 3 Sheets-Sheet l INVENTORS ATTO [Y .Ian. 16, 1962 J. o RUNCI ETAI. 3,017,046

BUCKET POSITION INDICATOR Filed May 11, 1959 '3 Sheets-Sheet 2 1952 J. o. RUNCI ETAI.

BUCKET POSITION INDICATOR 3 Sheets-Sheet 3 Filed May 11, 1959 IIHMJI United States Patent 3,017,046 BUCKET POSITION INDICATOR Joseph 0. Runci, Hudson, and Ralph J. Bernotas, South Euclid, ()hio, assignors to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed May 11, 1959, Ser. No. 812,269 15 Claims. (Cl. 214-140) This invention pertains to a position indicating mechanism and, in particular, to such a mechanism for indicating a selected position for the material handling bucket of a front end loader vehicle.

Loader vehicles of the type to which reference is made herein typically comprise a vertically adjustable boom structure pivotally connected at one end to the vehicle and pivotally supporting at the other end thereof a loader bucket adapted to dig, carry and discharge a load. Various types of tilt mechanisms or linkages have been developed for controlling tilting movement of the bucket on the boom for the purpose of disposing the bucket in various positions such as digging and dumping positions to receive and discharge a load, respectively.

One type of tilt mechanism comprises a fluid operated extensible and retractable jack directly pivotally connected to the boom structure and the bucket or, in eflect, a fluid operated latch controlling the bucket position irrespective of movement of the boom structure. Another type of tilt linkage is often referred to as forming a distorted parallelogram operatively pivotally connected to the vehicle, boom structure and bucket. The advantage of this type of linkage is that the bucket is automatically rolled either forwardly or backwardly or both relative to its pivotal connection to the boom as the latter is ele vated, and although the tilt linkage itself is not actuated. More often than not there is relatively great degree of relative movement between the bucket and its supporting boom structure as a result of the use of such a parallelogram type tilt linkage. Still another type of bucket support and tilt linkage involves an intermediate yoke structure pivotally connected to one end of the boom structure and supporting the loader bucket. The tilting jack or other means operates between the yoke structure and the bucket to pivot the latter relative to the yoke. Additional tilt means acts between the yoke structure and the vehicle or boom structure to provide some degree of automatic rolling or pivoting movement of the yoke relative to the boom as the latter is elevated, although this movement is very slight compared to the distorted parallelogram type tilt linkage aforementioned.

In loader vehicles of this type, irrespective of the particular type of tilt or bucket support linkage involved, a particular problem is encountered by the operator in properly positioning the loader bucket when in a low level position. This problem is presented due to the fact that the loader linkage extends forwardly from the vehicle operators compartment and obstructs his view of the bucket when in the low level position. Therefore, the operator experiences difiiculty in properly positioning the bucket in a selected position such as, for example, a low level digging position.

Various suggestions have been made as to a bucket position indicator which will apprise the vehicle operator when his bucket is in a selected position such as the digging position. However, such suggested indicating mechanisms do not provide a solution to the problem of indicating bucket position irrespective of what type of loader linkage or bucket support mechanism is involved. For example, in the simple fluid latch type of tilt mechanism aforedescribed, there is no automatic rolling movement between the bucket and the boom as the latter is elevated. Accordingly, a relatively simple indicating means can be employed to measure when the tilt jack has obtained a length corresponding to the digging position. However, such simple devices are not acceptable where a loader linkage is involved which comprises means for automatically rolling the bucket relative to the boom structure. In instances in which the bucket is supported by an intermediate yoke structure aforedescribed, one indicating mechanism has been designed to measure relative angularity between the bucket and the intermediate yoke structure. Such a mechanism appears to be acceptable inasmuch as not too drastic automatic rolling occurs between the bucket and yoke structure as the latter is lowered from a high lift dump position.

However, the heretofore proposed bucket indicating mechanism which is used with some success on bucket linkages including an intermediate yoke structure is not entirely acceptable for use with the loader comprising loader linkage of the distorted parallelogram type. As aforementioned, such linkages are specifically intended to automatically roll the bucket quite drastically relative to its supporting boom structure as the latter is elevated or lowered. The principal purposes of such a linkage is first, to break the bucket away from the load rapidly after digging and, secondly, to maintain the bucket in a substantially horizontal non-spilling attitude during vertical adjustment of the supporting boom structure. With such a distorted parallelogram type link-age, the relative pivoting movement between the bucket and its supporting boom is so drastic that prior indicating mechanisms designed to measure such relative movement are incapable of indicating at a high lift dump position the bucket position which will automatically result in obtaining a digging position when the boom is lowered.

It is, therefore, a general object of this invention to provide a mechanism for indicating the length of a fluid operated jack of the type employed in loader bucket tilt linkages.

It is another object and feature of this invention to provide a mechanism for indicating a desired position of an implement mounted on a support linkage which will indicate said position irrespective of the type of linkage employed and irrespective of boom elevation.

It is yet a more specific object of this invention to provide a mechanism for indicating the position of a bucket controlled by a parallelogram type tilt linkage, and which mechanism will indicate, irrespective of bucket elevation, a selected position such as a low level digging position.

'It is yet another object and feature of this invention to provide an indicating mechanism as aforedescribed which is relatively simple and compact in construction, may be adapted to any one of the various types of loader linkages, and which will provide a clear unobstructed view to the operator of the bucket position irrespective of the elevation of the bucket.

It is yet another object and feature of this invention to provide a bucket position indicator of the type aforementioned which directly measures the length of the tilt jack of the bucket tilt linkage and, as a result, clearly indicates a selected bucket position at any elevation thereof.

In general, these and other objects of this invention are attained in an indicator mechanism including a pivotally mounted pointer and indicia on the cylinder of a tilt jack or ram. The pointer is adapted for movement relative to the indicia in response to extension and retraction of the jack so as to measure the length of the latter. The pointer is provided with a cam follower means cooperating with a cam operating means rigidly secured to the piston element of the jack for movement therewith. As a result, the cam operator engages the cam follower means on the pointer to dispose the latter relative to the indicia in accordance with relative extension and retraction of the jack. Thus, the pointer makes its indications solely in response to a particular jack length which corresponds to a particular bucket position desired.

These and other objects and features of this invention as well as the manner in which they are attained will become more apparent hereinafter as the description of the invention proceeds, and in which reference is made to the following drawings in which:

FIGURE 1 is a side elevation of a front end loader vehicle with parts broken away to illustrate certain details of the invention;

FIGURE 2 is a fragmentary enlarged view of FIGURE 1 illustrating certain details of the bucket positioning mechanism; and

FIGURE 3 is a view taken on line 33 of FIGURE 2.

Referring now to FIGURE 1, there is shown a loader vehicle 2 having an operators station 4 and power means connected in drive transmitting relationship with the front and rear vehicle wheels 6 and 8, respectively. A loader Support and linkage mechanism 10 is disposed at the front end of the vehicle. It will be readily apparent to those skilled in the art that that portion of the loader support mechanism and linkage associated with the left side of the vehicle is shown in FIGURE 1 of the drawings, it being understood that identical structure is associated with the right side of the vehicle. Accordingly, reference will only be made to the structure on the left side of the vehicle.

A support pillar 12 is rigidly secured to the frame structure of the vehicle and includes an upwardly extending pillar or post portion 14 and a similar downwardly extending post portion 16. The loader boom 18 has its rearward end pivotally connected at 20 to the pillar portion 14 and extends forwardly and downwardly in front of the front vehicle axle. The bucket 22 is pivotally connected at 24 to the forward end of the boom structure 1-8, and includes transversely spaced side walls 26 joined by a bottom wall 28, and a cutting edge 30 extending along the forward edge of the bottom wall at the front of the bucket. A boom lifting jack or hoist 32 has one end pivotally connected at 34 to the lower piilar portion 16, and its other end pivotally connected at 36 intermediate the ends of the boom 18.

The bucket tilt linkage is of the distorted parallelogram type and includes a tilt lever 38 pivotally connected at 40 to the boom 18. A rigid link 42 is pivotally connected at 44 to the upper end of the tilt lever 38 and at 46 to the upper pillar portion 14. A double acting hydraulic hoist or jack 48 has one end pivotally connected at v50 to the lower end of the tilt lever 38, while the other end of the hoist is pivotally connected at 52 to the bucket22.

It will be readily appreciated that a suitable hydraulic system including a manual selector valve is employed to selectively supply fluid to the lower ends of the boom jacks 32 to elevate the boom structure. Ordinarily, the boom jacks are of the single acting variety inasmuch as gravity is relied upon for returning the boom structure to its lower position as shown in the drawing. The tilt jack 48 is double acting so as to be extensible and retractable from the position shown in the drawing to position the bucket as required.

In the operation of a loader mechanism of this type,

- it will be understood that the tilt jack 48 may be selectively extended and contracted to dispose the bucket 22 in any one of several positions. For example, in the position shown in FIGURE 1, the jack 48 is in an intermediate position disposing the bucket 22 in a low level digging position in which the forward portion of the bottom wall 28 of the bucket is disposed substantially horizontal or parallel to the ground. After digging in this position, the hoist 48 may be contracted substantially all the way to pivot the bucket 22 clockwise about the pivot point 24 to a low level load retaining position. Thereafter, the boom jack 32 may be extended to move the boom 18 to a high lift position. At this time, the

K tilt jack 48 may be extended substantially all the way to pivot the bucket 22 about pivot point 24 to a high lift dumping position.

From the above description of the loader operation, it may be said that such a loader mechanism has two extreme bucket positions; that is, a low level load retaining position in which the hoist 48 is substantially fully contracted, and the high lift dumping position in which the hoist is substantially fully extended. The aforementioned digging position, as shown in FIGURE 1 of the drawings, is intermediate these two extreme bucket positions. With the bucket in a low level position, it is quite difficult for the vehicle operator to dispose the bucket in such a digging position inasmuch as he has an obstructed view of the bucket.

This distorted parallelogram type tilt linkage aforedescribed has found considerable favor in the earth working trade because it automatically functions to maintain the bucket in a load holding attitude as the support booms are elevated. For example, assuming that a load has been received in the bucket, the tilt jack 48 may be retracted to the low level load retaining position at which time the bucket is rolled rearwardly a small amount about the pivot point 24. As the boom hoist 32 is extended, the geometry of the tilt linkage serves to automatically roll the bucket forwardly about the pivot point 24 so as to maintain the bucket in a non-spilling attitude; that is, a position in which the mouth of the bucket is maintained substantially horizontal or parallel with the ground. In some linkage structure, the distorted parallelogram construction not only serves to maintain the bucket in a non-spilling attitude, but is also employed to initially roll the bucket rapidly rearwardly upon breaking the bucket from the load at the low level digging position. Irrespective of whether or not the tilt linkage is employed for one or the other or both of these functions, and as is well known in the art, it should be noted that relative movement between the bucket and boom structure is relatively drastic, particularly in the lower range of boom movement.

Referring now particularly to FIGURES 2 and 3, the bucket position indicating mechanism 54 may be seen to comprise a support plate or bracket 56 adapted to nest about the tubular housing 58 forming a passage for the fluid to actuate tilt jack 48. A U-bolt 60 tightly engages the housing 58 and is suitably fastened to the plate 56. Intermediate its ends, the plate 56 is curved horizontally forwardly and terminates in a substantially vertically upstanding portion 62 which is curved laterally inwardly of the loader vehicle. Suitable indicia 64 is provided on the laterally inward edge of the mounting plate.

An indicator pointer 66 is pivotally mounted intermediate its ends to the bracket portion 62 by means of the pivot pin 68 and key 70, a torsion spring 72 being wound about the pin and having its ends respectively engaged with the pointer 66 and seated within an aperture in the bracket portion 62. The torsion spring normally biases the pointer toward engagement with a stop plate 74 secured to the mounting bracket portion 62. The pointer is of bell crank configuration so that its lower end projects toward the tilt jack 48 as shown particularly in FIGURE 3. At its lower end, the pointer is provided with a generally V-shaped cam follower 76 of substantially tubular cross section.

A tubular rod 78 has its forward end fixed to the piston rod of the tilt jack 48, and extends rearwardly through an elongate curved aperture 80 in the mounting plate portion 62. It will be noted that the axis of the rod 78 is substantially parallel to the axis of the tilt jack 48 and pivot pin 68. A cam operator 82 is secured to the free end of rod 78.

The cam operator 82 includes a relatively gently inclined cam surface 84 terminating in a relatively steeply and reversely inclined rear cam surface '86. As-is shown particularly in FIGURE 3, the cam operator is disposed at an angle to a vertical plane through the longitudinal axis of the rod 78. As will be readily apparent, the cam operator 82 is reciprocated along an axis substantially parallel to the axis of the jack 48 as the latter is extended or retracted and, accordingly, engages the cam follower 76 to position the indicator 66 relative to the indicia 64.

To install the bucket position indicator, the loader linkage is first disposed as shown in FIGURE 1 of the drawings with the bucket in a digging position. At this time, the jack 48 is in a corresponding position and, of course, at any time that the tilt jack obtains this length, the bucket will be disposed in the corresponding attitude relative to boom 18 for placement in the digging position at the time the bucket boom is lowered. The mounting bracket 56 is placed on the tubular housing 58 and adjusted thereon until such time as engagement of the inclined cam face 84 with the cam follower means 76 disposes the pointer opposite the indicia 64 as shown in FIGURE 3 of the drawings. The U-bolt it) is then tightened, and the indicator apparatus is oriented relative to jack length so as to indicate bucket digging po sition.

In operation, it may be assumed that a load is received in the bucket 22 with the latter and its support linkage disposed in the low level digging position as shown in FIGURE 1. Thereafter, the tilt jack 48 may be cont-raoted to place the bucket in the low level load retaining position aforementioned. During such retraction, the cam operator 82 is reciprocated rearwardly causing the inclined cam surface 84 to ride rearwardly away from the cam follower 76. As a result, the cam follower progressively rides down the inclined plane 84 and the pointer is pivoted upwardly in FIGURE 3 away from the indicia 64. Upward movement of the pointer in this manner indicates that the bucket is being pivoted upwardly to a load retaining position.

Thereafter, the boom jacks 32 may be actuated to elevate the booms 18 to a high lift position. During this movement, the bucket 22 will be rolled automatically about the pivot point 24 to maintain the bucket in a non-spilling attitude with respect to the ground. As aforementioned, this automatic rolling movement relative to the boom structure 18 is relatively great particularly upon initially elevating the booms 18.

In order to dump the bucket at the high lift position, the tilt jack 48 is then extended substantially to its full length causing the cam operator 82 to ride forwardly past the cam follower 76. As the inclined cam surface 84 rides past the cam follower, it will be readily apparent that the pointer 66 will ride downwardly past the indicia 64 until such time as the end of the cam surface 84 is reached. This range of downward movement of the pointer indicates that the bucket is being tilted downwardly for dumping. As the surface 84 of the cam operator rides past the cam follower 76, the latter is immediately freed and the spring 72 rapidly moves the pointer 66 against the stop 7 4.

After so dumping a load, the vehicle operator begins to contract the tilt jack 48. In so contracting this jack, the steeply inclined cam surface 86 of the cam operator initially engages the cam follower 76 of the pointer 66. Due to the steep inclination of the cam surface 86, the pointer 66 is moved rapidly from the stop 74 to its extreme lowermost position, at which time the higher or peak end of the cam surface 84 comes intoengagement with the cam follower. Continued retraction of the tilt jack causes the pointer 66 to move from its lowermost position upwardly toward the indicia 64. Again, this type of pointer movement indicates that the bucket is being pivoted upwardly. As the pointer reaches alignment with the indicia, tilt jack retraction is discontinued by the operator and the bucket is disposed so as to assume the digging position automatically when the boom 18 is lowered.

At this juncture, it should be noted that the pointer assembly is mounted so as to give an accurate indication of a bucket digging position irrespective of the elevation of the boom 13; that is, such indication is related solely to the length of the tilt jack 48 so that the bucket can be positioned as desired at any boom elevation. Moreover, since the indicating function is related solely to jack length, such an indicating mechanism may be employed on any loader linkage tilt jack irrespective of the particular type of tilt linkage employed. More importantly, such a positioning mechanism is particularly adapted for use in a parallelogram type tilt linkage as herein disclosed inasmuch as it will give an accurate indication of the digging position at high lift elevation of the boom 18 even though the tilt linkage subjects the bucket to relatively drastic movement relative to the boom structure in lowering and raising the boom.

Additionally, it may be noted that the pointer 66 is so designed as to give a uniform rate or degree of movement corresponding to a given increment of tilt jack movement. In this regard, the pointer 66 is of bell crank configuration so as to be able to dispose the rod 78 as close as possible to the tilt jack 48. Because of the bell crank configuration of the pointer, the shape of the cam follower 76 is so designed with respect to the inclined cam surface 84 of the cam operator so as to give a substantially constant effective torque arm for moving the pointer 66 about the pin 68. However, if it is desired to accelerate pointer movement or otherwise magnify its movement when the digging position is being approached, such a result may be achieved in several ways, one of which would require placing a rather sharp peak at the apex of the V-shaped cam follower 76 which will provide increased or accentuated travel for the pointer for a given jack movement upon approaching the digging position or, for that matter, upon passing such a position.

Although the above described apparatus is intended primarily to indicate when a loader bucket is in a digging position, such a mechanism will also indicate to some extent the position of the bucket to either side of the digging position. In the embodiment shown, movement of the tilt jack piston rod approximately two inches to either side of the reference position shown in FIG- URE 1 corresponds to pivotal movement of the bucket of approximately two and one half degrees to either side of the bucket digging position. In particular, this indicating apparatus provides a convenient means for the operator to control the disposition of the bucket cutting edge 30 below the horizontal as, for example, for dozing operations.

While but one form of the invention has been selected for an illustration thereof, other forms will be apparent to those skilled in the art. Therefore, the embodiments shown in the drawing are merely for descriptive purposes, and is not intended to limit the scope of the invention which is defined by the claims which follow.

We claim:

1. In a loader vehicle, the combination comprising a vertically adjustable boom pivoted at one end to said vehicle, a material handling implementpivoted at the other end of said boom, a tilt linkage operatively connee-ted between said vehicle and implement for tilting the latter about said boom and comprising a fluid-operated jack including relatively movable piston and cylinder members, mechanism for indicating a selected position of said implement irrespective of boom elevation, said mechanism comprising a support fixed to one of said members, indicia on said support, an indicator pointer pivotally mounted intermediate its ends on said support, one end of said pointer cooperating with said indicia to indicate jack length, follower means at the other end of said pointer, and cam means supported J on the other of said members and including an inclined cam surface engageable with said follower means upon reciprocation of said jack to pivot said pointer relative to said indicia.

2. In a loader vehicle, the combination comprising a vertically adjustable boom pivoted at one end to said vehicle, a material handling implement pivoted at the other end of said boom, a tilt linkage operatively connected between said vehicle and implement for tilting the latter about said boom and comprising a fluid-operated jack including relatively movable piston and cylinder members, mechanism for indicating a selected position of said implement irrespective of boom elevation, said mechanism comprising a support fixed to one of said members, indicia on said support, an indicator pointer pivotally mounted intermediate its ends on said support, one end of said pointer cooperating with said indicia to indicate jack length, follower means at the other end of said pointer, cam means supported on the other of said members and including an inclined cam surface engageable with said follower means upon reciprocation of said jack to pivot said pointer relative to said indicia, and yieldable spring means acting on said pointer to oppose movement of the latter in one direction.

3. In a loader vehicle, the combination comprising a vertically adjustable boom pivoted at one end to said vehicle, a material handling implement pivoted at the other end of said boom, a tilt linkage operatively connected between said vehicle and implement for tilting the latter about said boom and comprising a fluid-operated jack including relatively movable piston and cylinder members, mechanism for indicating a selected position of said implement irrespective of boom elevation, said mechanism comprising a support fixed to one of said members, indicia on said support, an indicator pointer pivotally mounted intermediate its ends on said support, one end of said pointer cooperating with said indicia to indicate jack length, follower means at the other end of said pointer, cam means supported on the other of said mempointer, cam means comp-rising a relatively gently inclined cam surface initially engageable with said follower means upon extension of said jack to pivot said pointer in one direction on said support, and a relatively steep reversely inclined cam surface successively engageable with said follower means upon extension of said jack beyond a predetermined extent to release said pointer for movement in the opposite direction, yieldable spring means acting on said pointer to urge the latter continuously in said opposite direction, and stop means on said support limiting movement of said pointer in said opposite direction.

4. In a loader vehicle, the combination comprising a vertically adjustable boom pivoted at one end to said vehicle, a material handling implement pivoted at the other end of said boom, a tilt linkage operatively connected between said vehicle and implement for tilting the latter about said boom and comprising a fluid-operated jack including relatively movable piston and cylinder members, mechanism for indicating a selected position of said implement irrespective of boom elevation, said mechanism comprising a support fixed to one of said members, indicia on said support, an indicator pointer pivotally mounted intermediate its ends on said support, one end of said pointer cooperating with said indicia to indicate jack length, fol-lower means at the other end of said pointer, and cam means including an inclined cam surface supported on the other of said members and engageable with said follower means upon reciprocation of said jack to pivot said pointer relative to said indicia, said cam surface and cam follower means being so shaped relative to each other to provide a predetermined increment of pointer movement in response to an increment of jack reciprocation.

5. In a loader vehicle, the combination comprising a vertically adjustable boom pivoted at one end to said vehicle, a material handling implement pivoted at the other end of said boom, a tilt linkage operatively connected between said vehicle and implement for tilting the latter about said boom and comprising a fluid-operated jack including relatively reciprocable piston and cylinder members, mechanism for indicating a selected implement position irrespective of boom elevation, said mechanism comprising a support fixed to said cylinder and upstanding therefrom, indicia on said support, an indicator pointer pivotally mounted intermediate its ends on said support for rotation about an axis above and substantially parallel to the axis of said jack, one end of said pointer cooperating with said indicia to indicate jack length, cam follower means at the other end of said pointer, a rod secured to said piston and extending between said cylinder and pointer on an axis substantially parallel to the axis of said jack, cam means secured to said rod and including an inclined cam surface engageable with said follower means upon extension of said jack to pivot said one pointer end in one direction on said support, and yieldable spring means acting on said pointer to oppose movement of the latter in said one direction.

6. In a loader vehicle, the combination comprising a vertically adjustable boom pivoted at one end to said vehicle, a material handling bucket pivoted at the other end of said boom, a tilt linkage operatively connected between said vehicle and bucket for tilting the latter about said boom, said tilt linkage comprising a fluid-operated jack including relatively reciprocable piston and cylinder members, said linkage being of the type causing automatic pivoting of the bucket about the connection of the latter to said boom as the bucket is elevated or lowered from and to a low level digging position, mechanism for indicating the digging position of said bucket at any boom elevation, said mechanism comprising a support fixed to one of said members, indicia on said support, an indicator pointer pivotally mounted intermediate its ends on said support, one end of said pointer cooperating with said indicia to indicate jack length, follower means at the other end of said pointer, and cam means secured to the other of said members and including an inclined cam surface engageable with said follower means upon reciprocation of said jack to pivot said pointer relative to said indicia.

7. In a loader vehicle the combination comprising a vertically adjustable boom pivoted at one end to said vehicle, a material handling bucket pivoted at the other end of said boom, a tilt linkage operatively connected between said vehicle and bucket for tilting the latter about said boom, said tilt linkage comprising a fluid-operated jack including relatively reciprocable piston and cylinder members, said linkage being of the type causing automatic pivoting movement of said bucket about the connection of the latter to said boom as the bucket is elevated or lowered from and to a low level digging position, mechanism for indicating the digging position of said bucket at any boom elevation, said mechanism comprising a support fixed to said cylinder and upstanding therefrom, indicia on said support, an indicator pointer pivotally mounted intermediate its ends on said support for rotation about an axis above and substantially parallel to the axis of said jack, one end of said pointer cooperating with said indicia to indicate jack length, the other end of said pointer being bent downwardly from the pivotal mounting of said pointer towards said jack, cam follower means at said other pointer end, a rod secured to said piston and extending between said cylinder and pointer on an axis substantially parallel to the axis of said jack, cam means secured to said rod, said cam means comprising a relatively gently inclined cam surface initially engageable with said follower means upon extension of said jack to pivot said one pointer end in one direction on said sup port, and a relatively steep reversely inclined cam surface successively engageable with said follower means upon extension of said jack beyond a predetermined extent to release said pointer for movement in the opposite direction, yieldable spring means acting on said pointer to urge the latter continuously in said opposite direction, and stop means on said support limiting movement of said pointer in said opposite direction.

8. In a loader vehicle, the combination comprising a vertically adjustable boom pivoted at one end to said vehicle, a material handling bucket pivoted at the other end of said boom, a tilt linkage operatively connected between said vehicle and bucket for tilting the latter about said boom, said tilt linkage comprising a fluidoperated jack including relatively reciprocable piston and cylinder members, said linkage being of the type causing automatic pivoting movement of said bucket about the connection of the latter to said boom as the bucket is elevated or lowered from and to a low level digging position, mechanism for indicating the digging position of said bucket at any boom elevation, said mechanism comprising a support fixed to said cylinder and upstanding therefrom, indicia on said support, an indicator pointer pivotally mounted intermediate its ends on said support for rotation about an axis above and substantially parallel to the axis of said jack, one end of said pointer cooperating with said indicia to indicate jack length, the other end of said pointer being bent downwardly from the pivotal mounting of said pointer towards said jack, cam follower means at said other pointer end, a rod secured to said piston and extending between said cylinder and pointer on an axis substantially parallel to the axis of said jack, cam means secured to said rod, said cam means comprising a relatively gently inclined cam surface initially engageable with said follower means upon extension of said jack to pivot said one pointer end in one direction on said support, and a relatively steep reversely inclined cam surface successively engageable with said follower means upon extension of said jack beyond a predetermined extent to release said pointer for movement in the opposite direction, said gently inclined cam surface and cam follower means being so shaped relative to each other so as to give a substantially constant effective torque arm for moving said pointer about its pivotal mounting, yieldable spring means acting on said pointer to urge the latter continuously in said opposite direction, and stop means on said support limiting movement of said pointer in said opposite direction.

9. A mechanism for indicating the length of a fluid pressure operated jack including relatively reciprocable piston and cylinder members, said mechanism comprising a support fixed to one of said members, indicia on said support, an indicator pointer pivotally mounted intermediate its ends on said support, one end of said pointer cooperating with said indicia to indicate jack length, follower means at the other end of said pointer, and cam means supported on the other of said members and including an inclined cam surface engageable with said follower means upon extension and retraction of said jack to pivot said pointer relative to said indicia.

10. A mechanism for indicating the length of a fluid pressure operated jack including relatively reciprocable piston and cylinder members, said mechanism comprising a support fixed to one of said members, indicia on said support, an indicator pointer pivotally mounted intermediate its ends on said support on an axis substantially parallel to the axis of said jack, one end of said pointer cooperating with said indicia to indicate jack length, follower means at the other end of said pointer, and means including an inclined cam surface supported on the other of said members for movement relative to said follower means on an axis substantially parallel to the axis of said jack, said cam surface being operable on said follower means in response to reciprocation of said jack to pivot said pointer relative to said indicia.

11. A mechanism for indicating the length of a fluid pressure operated jack including relatively reciprocable piston and cylinder members, said mechanism comprising a support fixed to one of said members, indicia on said support, an indicator pointer pivotally mounted intermediate its ends on said support, one end of said pointer cooperating with said indicia to indicate jack length, follower means at the other end of said pointer, means including an inclined cam surface supported on the other of said members for movement relative to said follower means, said cam surface being operable on said follower means upon extension of said jack to pivot said pointer in one direction on said support, and yieldable spring means acting on said pointer to oppose movement of the latter in said one direction.

12. A mechanism for indicating the length of a fluid pressure operated jack including relatively reciprocable piston and cylinder members, said mechanism comprising a support fixed to one of said members, indicia on said support, an indicator pointer pivotally mounted intermediate its ends on said support, one end of said pointer cooperating with said indicia to indicate jack length, follower means at the other end of said pointer, means including a cam supported on the other of said members for movement relative to said follower means in response to jack reciprocation, said cam comprising a relatively gently inclined cam surface initially engageable with said follower means upon extension of said jack to pivot said pointer in one direction on said support, and a relatively steep reversely inclined cam surface successively engageable with said follower means upon extension of said jack beyond a predetermined extent to release said pointer for movement in the opposite direction, yieldable spring means acting on said pointer to urge the latter continuously in said opposite direction, and stop means on said support limiting movement of said pointer in said opposite direction.

13. A mechanism for indicating the length of a fluid pressure operated jack including relatively reciprocable piston and cylinder members, said mechanism comprising a support fixed to one of said members, indicia on said support, an indicator pointer pivotally mounted intermediate its ends on said support, one end of said pointer cooperating with said indicia to indicate jack length, and cam follower means at the other end of said pointer, and means including an inclined cam surface supported on the other of said members and in engagement with said cam follower means to pivot said one pointer end relative to said indicia in response to jack reciprocation, said cam surface and cam follower means being so shaped relative to each other so as to give a substantially constant effective torque arm for moving said pointer about its pivotal mounting during jack reciprocation.

14. A mechanism for indicating the length of a fluid pressure operated jack including relatively reciprocable piston and cylinder members, said mechanism comprising a support fixed to said cylinder and upstanding therefrom, indicia on said support, an indicator pointer pivotally mounted intermediate its ends on said support for rotation about an axis above and substantially parallel to the axis of said jack, one end of said pointer cooperating with said indicia to indicate jack length, the other end of said pointer being bent downwardly from the pivotal mounting of said pointer towards said jack, cam follower means at said other pointer end, a rod secured to said piston and extending between said cylinder and pointer on an axis substantially parallel to the axis of said jack, cam means secured to said rod, said cam means comprising a relatively gently inclined cam surface initially engageable with said follower means upon extension of said jack to pivot said one pointer end in one direction on said support, and a relatively steep reversely inclined cam surface successively engageable with said follower means upon extension of said jack beyond a predetermined extent to release said pointer for movement in the opposite direction, yieldable spring means acting on said pointer to urge the latter in said opposite direction, and stop means on said support limiting movement of said pointer in said opposite direction.

15. In a loader vehicle, the combination comprising a vertically adjustable boom pivoted at one end to said vehicle, a material handling bucket pivoted at the other end of said boom, a tilt linkage operatively connected between said vehicle and bucket for tilting the latter about said boom, said tilt linkage comprising a fluid-operated jack including relatively reciprocable piston and cylinder members, said linkage being of the type causing automatic pivoting of the bucket about the connection of the latter to said boom as the bucket is elevated or lowered 10 from and to a low level digging position, mechanism for indicating the digging position of said bucket at any boom elevation, said mechanism comprising indicia and a cooperable indicator pointer supported on one of said members, and operating means supported on the other of said members and operably connected to said indicator pointer for movement of the latter relative to said indicia in response to reciprocation of said jack.

References Cited in the file of this patent UNITED STATES PATENTS 505,652 Greene Sept. 26, 1893 2,030,529 Nash Feb. 11, 1936 2,517,582 Hull Aug. 8, 1950 2,589,896 Toland Mar. 18, 1952 2,668,631 Reese Feb. 9, 1954 2,883,077 Pilch Apr. 21, 1959 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIQN Patent No. 3,017 046 January, le i962 Jeseph 0., Runeiet all It is hereby certified that error appears in the above numbered pat ent requiring correction and that the said Letters Patent should read as corrected below Column 4 line l6 for "This" read The line 30, fer structure reed struetures eelumn 7 lines 39 and 40, fer "mempeinter read members said eelumn 12 line l0 fer l-lull read Lull Signed and sealed this 1st day ef May 1962,

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patent 4 

